Feed water regulating apparatus for boilers



June 9.46. H. A. SCHLIEDER 1,

FEED WATER REGULATING APPARATUS FOR BOILERS Filed Oct. 2} 1944 2 SheetSSheGt l INVENTOR. HAROLD A. SCHL/EDER wwfmw HTTORNEY June 4,1946. H. A.SCHLIEDER 2,401,512

FEED WATER REGULATING APPARATUS FOR BOILERS Filed'Oct. 2, 1944 2Sheets-Sheet 2 v 'INVENTOR. v HHROLQA. JCHLIEDE'R -w. fismaw A TTORNEYPatented June 4, 1946 FEED WATER REGULATING ArPA R-A'riis FOR BOILERS IV Harold Augustus Schlieder, Erie, Pa., assignor to Northern EquipmentCompany, Erie, Pa. a corporation of Pennsylvania Application October 2,1944, Serial No. 556,864

8 Claims.

This invention relates to boiler feed water regulating apparatus, andmore particularly to improved regulating apparatus of the typecomprising a thermostatic element responsive to boiler water levelvariations, a servo-motor operated control valve for the feed water, andmeans controlling the motor in accordance with thermal change in thethermostatic element.

It is a primary object of the invention to provide feed water regulatingapparatus for boilers which is of simple, compact, construction andadapted to efficiently feed the boiler.

Another object of the invention is to provide boiler feed waterregulating apparatus having a level responsive element highly sensitiveand quickly responsive to level variations.

Another object of the invention is to provide regulating apparatus ofthe above type comprising parts which may be installed as a unit withthe level responsive element bearing a. fixed relation to the normalwater level in the boiler.

and water therein and less total movement from the device. With myimproved arrangement most of the condensate will drain through the crossconnection. In instances where the steam is released violently withinthe boiler drum, or on marine installations where the water moves aroundwithin the drum, particles of water are frequently thrown into the steamconnection of the feed water regulator. In the present arrangement thesewater particles will drop through the cross connection and not becarried into the expansion tube.

Another advantage secured from the construction described is that thewater connection to theexpa'nsion tube canbe taken at a point in thecross connection corresponding to the height of the lower end of theexpansion tube. Heretofore, the water connection'oi level responsivedevices for feed water regulators has been taken di- According to theinvention a unit comprisin a cross connection conduit adapted to beconnected to the steam and water spaces of the boiler in a. conventionalmanner supports a conduit cornmunicating with the cross connection atthe top and below the normal boiler water level by a U shaped section.An intermediate portion of the conduit comprises a thermostatic tubewith the tube center disposed at the approximate normal boiler Waterlevel. The conduit supports a frame preferably formed of channel membersand forming the cold section of the unit. The thermostatic expansiontube, heated or cooled by changes in boiler water level, acts on a bellcrank lever pivoted to one end of the frame. The thermostat levermovement, multiplied or reduced by an auxiliary lever acts on a pilotvalve mounted on the frame. The pilot valve varies the pressure of relaysupply, or auxiliary source of energy, so that a servo mechanism willcause a feed water valve of any size to move in proportion to boilerwater level variations.

The cross connection in addition to supporting thelevel responsive tubeand associated parts acts as a separator permitting a supply of drysteam to be continuously furnished to the expansion tube. By connectingthe level responsive tube directly to the cross connection instead ofdirectly to the steam and water spaces of the boiler improvedperformance is secured. With conventional connections, all steamcondensing in the piping above the expansion tube runs through thetubeand keeps the water in the lower part hot, resulting in less temperaturedifference between the steam re'ctly'lfrom the boiler at "an openingwell below the minimum safe Water level. With such a hook-up,1asthelevel in the boiler falls unusually low it also falls in thethermostatic element or expansion tube and connecting piping. Steamfollows" the level down through the expansion tube and sometimes welldown into the piping below the tube. The steam heats'this piping andwhen the level rises again the water passing through the hotsection'absorbs heat from the pipe as it rises. Up'on'reaching theactive section of the expansion tube it may be so hot that it will notcause the tube to control as required.

The use of a, cross connection eliminates this condition since during anextreme drop in boiler water level, the water will drop in the crossconnection below the point at which the water connection to theexpansion tube is made but since this water connection includes a loopforming a trap, the water cannot drop below the end of the expansiontube When the Water level rises the cool water retained in the loopwillenter the exparis'i'on tube and cause the regulator to respond moreaccurately andlrapidly than otherwise,

A further advantage of the cross connection is the provision of a levelresponsive device wherein the elevation of the waterlevel in the tubeand in the boiler drum maintains a more nearly constant relationship.Due to the difference in density of the fluid in the boiler drum andexpansion tube, the. level is lower in the tube than in the boiler. Inprior constructions with which I am familiar, the amount by which thethermostat water level is relatively lower was dependent on theinstallation and influenced by the locationof the water connection atthe drum head and by the'distance boiler as indicated at 22 and 23, theupper end of the expansion tube having an enlarged collar or heel piece24 secured thereto and the lower end a head piece collar 26, bothcollars preferably being secured by welding. Also, the conduit M ispreferably weld connected to the cross connection ll I Priorconstructions with which I amiamiliar have employed elbow like head andheel pieces at each end of the expansion tube to effect pipingto theboiler. Elimination of these masses of metal which stored or releasedheat with water level variations with resultant less radiation from Fig.1 is an end elevational view, largely di'agrammatic, of a boiler drumand my improved regulating apparatus.

Fig. 2 is a side elevational-view of the regulating apparatus of Fig. 1and a portion of the boiler drum.

Fig. 3 is a longitudinal sectional view of a type of thermostatic tube Ipreferably employ.

Fig. 4 is an enlarged viewof a portion of the apparatus illustrated inFig. 1 with parts broken awayfor clearness of illustration.

Fig. 5 is a vertical medial sectional view of a 'fiuid'pressure motorand associated feed water valve I may employ, and

Fig. 6 is aside .elevational view of the motor and valve illustrated in5;

Referring now to the drawings, and particularly Figs. 1 and 2, I haveindicated a conventional'boiler drum at 10 anda cross connectionextending between the steam and water spaces of the drum generally atII. Valves [2 and I3 are provided in the cross connection forcontrolling communication between the cross connection conduit and theboiler. Supported from the cross connection II is a conduit generallyindicated at It communicating with the top portion of the crossconnectionas indicated at 16 and with a point thereof below the normalboiler waterilevel asindicated at 11-. Conduit l4 includes'an incanestube I8 adapted to change length under thermal change. The center of thethermostat or expansion tubejlB is disposed at the approxi-r mate normalboiler water level with the lower or water'connection end thereofdisposed at a height substantially corresponding to the point I! atwhich conduit 14 communicates with cross connection II. 'It will benoted that the section of conduit I4 below the thermostat I8 is ofgenerally U form including ahorizontal lower portion 19, the right handleg of this section being extended downwardly to communicate with adrainage valve 2|.

With this arrangement when there is an extreme, drop in boiler waterlevel the water will drop down below the point I! in the crossconnection 'H but due to the U form or loop section forming a trap thewater cannot drop below the end of the expansion tube 18. Upon a rise inboiler water level the cool water retained in the loop will enter theexpansion tube l8 and cause the regulator to' respond more accuratelyand rapidly than if the water connection of conduit 14 was .madedirectly'with the boiler drum. In a direct connection hookup as theboiler water level falls unusually low it also'would fall in conduit Mwith the steam following the'level and heating the conduit. "Waterpassing through this section upon a rise in level absorbs heat to theextent that it may not cause the thermostat to the-upper connection andless heat storage at the lower connection eifects more accurate responseto water levelvariations.

The conduit l4 or more specifically expansion tube [8 supports a framecomprising a pair of steel channel members 21 spaced laterally from andat each side of the expansion tube and interconnected at the top by ablock 28. A U shaped spacing element extending between the lower portionof the channel members is illustrated at 29.

The block 28 is threaded to receive an adjusting collar 3| which abutsthe expansion tube heel piece collar 24. Rotation of collar 3| will movethe frame longitudinally relative to the expansion tube ands, lock nut32 maintains the frame in an adjusted position. A pin 33 supported bythe channel members 21 forms a pivotal mounting for a generally L shapedbell crank lever '3 1. Lever 34 preferably has a'forkedend whichstradjdles the head piece collar'23 with the forks being notched toreceive aligned pins 3'5 extending from each side of the collar. A pairof tension springs 38 are secured to the free endof lever 34 and to thechannel members Z'L' The frame forms the cold section of the unit andupon an increase in thejlength ofjthe'expan sion tube due to a. drop ofwater level and" a corresponding increase in the steam therein the lever34 will be permitted to'rock in a clock-wise direction about' pin 33under the influence of springs 38. Upon'a rise in water level the tube[8 will contract rocking lever 34 in a counterclockwise direction aboutpin 33ag'ainst the tension of springs 38. A bracket 39 secured to theframe pivotally supports abell cranklever M which i continuously urgedin'a clock-wise direction by tends to a fluid pressure motor or servo a'spring 42 secured to the upstanding arm of the'lever and the bracket. Anelement 43'slidable along the lower arm of lever 4| and adapted to belocked at an adjusted position by 'a set screw or the likehas anadjusting pin 44 threaded thereinto which bears against the upper arm oflever 34. A look nut 46 holds pin 44 in a desired ad'- justed position.It will now be understood that clock-wise movement of lever 34 eifectscounter clock-wise movementof lever 4| or that the levers rotate aroundtheirpivotal points in reverse di-- rection V The upstanding arm oflever 4t bears against and actuates the stem'4'l of a pilot valve '48.The pilot valve is of a well known type wherein the pressure of fluidfrom a relay supply ats'ubstantially constant pressure will be varied inac cordancewith stem displacement. The lineto the relay supply isindicated M49 and the variable or controlled pressure line at'5 I; Line5 l exnism generally indicated at 52.

Fig's. ,4 and 5 illustrate a type of fluid pressure motor and feed watervalve which I may employ. Valves of this general type are wellknownwherein a servo mechanism will cause a vvalveflof any size'to movein" correspondence "with 'pre ss'ure mecha variations as controlled bythe pilot valve or in accordancewith boiler water-level variation actingon my improved regulating apparatus. The line 5! communicates with achamber '53 and upon an increase of pressure therein a diaphragm 54 andstem 56 are forced downwardlycausing the valve piston 51 to furtherclose the ports 58 and restrict flow from the inlet 59 to the outlet 5i. The underside of the diaphragm is exposed to atmosphere and downwardmovement of the stem is resisted by an adjustably mounted compressionspring 62 which aids opening movement of the valve upon a decrease inpressure in chamber 53.

It will now be understood that the expansion and contraction of'tube 18occurs between the heel piece collar 24 and head piece collar 28 withsprings 38 acting on lever 34 and pin 33 maintaining the frame firmlyagainst collar 24. Since collar 24 is fixed any change in length of tube18 causes collar 26 to move. Threaded collar 3| which bearsagainstcollar 24 may be screwed in or out effecting movement of theframe relative to the expansiontube 18 to efiecta coarse adjustment witha finer'adjustment bein obtained by manipulation of pin 4-4. Element 13may be moved along the lower arm of bell crank 1ever4l to relativelyincrease or reduce the response. 7 Referring now to Fig. 3; Ihaveshown-a type of expansion tube which I preferably employ wherein aseries of circumferential grooves 63, preferably square in crosssection, are formed in the external surface of the tube. A tube of thistype has decided advantages relative to a non-grooved tube in that thereduction in the amount of metal compared to the amount of water storedin the tube improves the rate of heating and cooling. About twice theradiating surface is provided thereby increasing the temperaturedifferential between the steam and water ends of the tube resulting inrelatively more movement. The reduction in cross sectional area of thepath by which heat is continually flowing along the tube from the steamend to the water end reduces the heat flow and increases the temperaturedifferential between the tube ends resulting in relatively moremovement.

Within practical limits I preferably employ a small size expansion tubesince a small diameter pipe has a larger ratio of surface to volume. Forexample, in the present apparatus I preferably use a expansion tuberather than a tube. The smaller cross-sectional area of the tube reducesthe amount of heat conducted from the hot to the cold end of the tubethrough the tube walls and the relatively larger surface ratio tends tocool the water in the tube at a faster rate. These two factors tend toincrease the amount of tube movement available by increasing thetemperature differential between the steam and Water. Also, a thinnergage tube than standard may be used to further reduce the wall area andpath for conduction of heat and the ratio of the amount of metal tovolume of water in the tube. This will further reduce the time lag,since with a rising level the walls of the tube being thinner will haveless heat to give up to the Water and the final temperature will beattained more rapidly.

The combination of features set forth above provides more temperaturediiference and hence greater movement for a given change in water levelthan in prior regulating apparatus of this 6 generaltype with which I amfamiliar and enables a relatively larger pilot valve to be moreaccurately operated wer longer stroke thereby eliminating the need forrelay supply amplifiers, or multipliers common to priorservo-motorequipment The apparatus described including the cross connection, theconduit and expansion tube supported thereby, the pilot valve,-fra-me,and levers supported by the tube may be assembled and installed as aunit merely by connecting the crossconnection with the boiler drum andthe line from the fluid pressure motor to the pilot valve. Also,connection will be made with the drainage valve. The level responsiveelement or expansion tube will then bear a desired fixed. relationshipto the normal boiler water level eliminating installation errors asmight occur if it was necessary to adjust the expansion tube relative tothe normal boi'ler water level at the time of installation of theapparatus on the boiler.

As previously pointed out, with conventional connections not employing across connection all steam condensing in the piping above the expansiontube and particles of water thrown thereinto runs through-the tubekeeping the water in the lower part of the expansion tube hot whereas inthe present arrangement most of the condensate will drainthrough thecross connection'with the cross connection acting as a separatorpermitting a supply of dry steam to be continuously supplied to theexpansion tube.

Ipreferably take the steamsupply to the expansion tube from the highestpoint of the cross connection ll since I have found that if it weretaken at a lower point which might be sealed off by a sudden rise inboiler Water level the expansion tube will be caused to contract closingthe regulating valve in a normal manner until the level reached thejunction point, then the expansion tube would heat up again and open thefeed valve When it should be closed. This ac tion is probably the resultof circulation within the inclined section of the tube when it iscompletely submerged.

The tube I8 is preferably formed of material having a high coefficientof expansion but this is not essential and I have found that a regulatorof the t pe herein described with the expansion tube formed of ordinarysteel pipe and having substantially the same coefiicient of expansion asthe frame or channel members 21 will operate satisfactorily. Therelative or operating movement secured is not dependent on thedifference in expansion coefficient but on the fact that the frametemperature remains substantially constant while the tube temperaturevaries with the water level therein.

Although I have shown and described a preferred embodiment of theinvention it is under stood that numerous and extensive departures maybemade therefrom without departing from the spirit of the invention andthe scope of the appended claims.

The invention is hereby claimed as follows:

1. Feed water regulating apparatus comprising parts adapted to beinstalled as a unit on boilers having a fiuid pressure motor operatedfeed water valve, said unit comprising a cross connection adapted to beconnected to the steam and water spaces of the boiler, a conduitsupported by the cross connection and communicating therewith at the topportion and at a point above the bottom portion and below the normallevel, an intermediate portion of the conduit being formed by tion bytube contraction, spring means urging the lever in a reverse direction,a pilot valve supported by the frame adapted to be connected to a relaysupply. of fluid and to the fluid pressure motor, the pilot valve havinga stem adapted to vary fluid pressure to the motor in accordance withstem displacement, and a second rock lever pivotally supported on theframe operable by the first rock lever and actuating the stem.

2. The regulating apparatus as described in claim 1 and wherein meansare provided for adjusting the frame longitudinally relative to thetube, and for adjusting the effect of the second rock lever on the stemfor a given movement of the first rock lever.

3. The regulating apparatus as described in claim 1 and wherein theconduit portion below the tube includes a loop having its lower portionat a fixed distance below the cross connection juncture with the boilerwater space.

4. The regulating apparatus as described in claim 1 and wherein the tubeis weld connected to the conduit portions communicating with theboiler..

5. The regulating apparatus as described in V 8 7 claim 1 and whereintheexpansion tubeis formed with a series of external circumferentialgrooves reducing the cross-sectional area of the heat path along thetube.

6. Feed water regulating apparatus for boilers comprising a boiler drum,across connection communicating with the water and steam space of thedrum at an end thereof, a tube communicating with the cross connectionadjacent its point of entry to the steam space and intermediate thenormal water level and the point of entry of the cross connection to thedrum water space, the tube including an inclined thermally expansibleportion, a frame extending along the tube incline portion and fixedthereto at one end of the frame, a generally L shaped lever pivotallymounted adjacent the other end of the frame and rockable by movement ofthe thermally expansible tube portion, a second lever mounted on theframe and adapted to transmit movement initiated by the first lever, afeed water valve, a fluid pressure motor controlling the feed watervalve, a pilot valve for the motor mounted on the frame, and the leversconjointly controlling operation of the pilot valve. V

'7. The apparatus as described in claim 6 and wherein both levers havespring means associated therewith to maintain the levers in operativerelationship.

8. The apparatus as described in claim 6 and wherein both levers haveadjustment means associated therewith. I

HAROLD AUGUSTUS SCHLIEDER.

